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10th Class Science Periodic Classification of Elements Question Bank Periodic Classification of Elements

  • question_answer
    Electronic configurations of elements P, Q, R and S are given below :
    P : 2, 8, 1;           Q : 2, 5
    R : 2, 8, 7;           S : 2, 8, 5
    Which of the following statements are correct? Elements O and S belong to the same
    I. period of the periodic table.
    II. P is an alkali metal.
    III.  R is a metal.
    IV. Valency of element S is 3.
     

    A) I and II only      

    B) II and IV only

    C) I and III only    

    D) All of these

    Correct Answer: B

    Solution :

    P (2, 8, 1) : group 1, alkali metal Q (2, 5) : period 2, Group 15, valency 3. R (2, 8, 7) : period 3, group 17, valency 1, non-metal S (2, 8, 5) : period 3, group 15, valency 3 non-metal


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